1. Field of the invention
The present invention relates generally to spark gap switches for high power ultra-wideband electromagnetic wave radiation for stabilized discharge and, more particularly, to a spark gap switch for high power ultra-wideband electromagnetic wave radiation which is configured such that it can have stabilized discharge characteristics that allow discharge to occur on central portions of electrodes, whereby the output power of radiated electromagnetic waves can be markedly stabilized.
2. Description of the Related Art
Generally, ultra-wideband electromagnetic wave generation sources refer to apparatuses which are widely used in fields, such as a field using ultra-wideband radar or a field involving the detection of buried objects. An ultra-wideband electromagnetic wave generation source typically includes an energy storage device which stores electric or magnetic energy, a switching device which generates ultra-wideband pulses from the stored energy, and an antenna which radiates ultra-wideband waves.
To increase the peak output power of electromagnetic waves radiated into space from such an ultra-wideband electromagnetic wave generation source, it is most important to increase the capacitance or inductance of the energy storage device, reduce mismatching between the switching device and the antenna, and enhance the electric insulation of the antenna.
The applicant of the present invention proposed a spark gap switch for high power ultra-wideband electromagnetic wave radiation in Korean Patent Registration No. 1015958, which can be used as a high power switching device and can conduct functions of storage of electric energy and generation and radiation of ultra-wideband electromagnetic pulses or waves.
FIGS. 1 and 2 illustrate the above-stated conventional spark gap switch for high power ultra-wideband electromagnetic wave radiation. As shown in FIGS. 1 and 2, the conventional spark gap switch for high power ultra-wideband electromagnetic wave radiation includes a casing 100, electrodes 111 and 112, a fixing bracket 120 and a movable bracket 121.
The casing 100 has a hollow cylindrical structure which has openings 101 and 102 in opposite ends thereof and is made of nonmetallic electric insulation material.
The electrodes 111 and 112 are disposed in the openings 101 and 102 of the casing 100 at positions spaced apart from each other by a predetermined distance in such a way that they face each other. The electrode 111 is a high-voltage electrode to which high voltage is supplied, and the other electrode 112 is a ground electrode which forms a potential difference with respect to the high-voltage electrode. The electrodes 111 and 112, when power is applied thereto, together conduct functions of storage of electric energy, generation of ultra-wideband electromagnetic, pulses and radiation of electromagnetic waves. Particularly, the spark gap switch is designed such that areas of surfaces of the electrodes 111 and 112 that face each other are comparatively large and the distance between the electrodes 111 and 112 is comparatively short, whereby the capacitance formed by the electrodes 111 and 112 can be enhanced. In other words, before functioning as a switch for generating electromagnetic pulses, the electrodes 111 and 112 are designed such that the capacitance at which an electric field is stored in the insulation space 115 defined between the electrodes 111 and 112 and the casing 100 is increased.
The fixing bracket 120 and the movable bracket 121 are made of electric insulation material in the same manner as that of the casing 100 and are installed in the electrodes 111 and 112. The fixing bracket 120 and the movable bracket 121 function to adjust the distance between the electrodes 111 and 112, fix the positions of the electrodes 111 and 112, and maintain gas pressure between the electrodes 111 and 112. The fixing bracket 120 is fixed in the opening 102 of the casing 100. The electrode 112 is fastened to the casing 100 by the fixing bracket 120. The movable bracket 121 has an external thread 122 and is threadedly coupled to the opening 101 of the casing 100 so that it can be movably installed in the opening 101 of the casing 100.
Cable guides 125 are provided in the fixing bracket 120 and the movable bracket 121. High-voltage cables through which high-voltage is supplied to the electrodes 111 and 112 are guided into the corresponding electrodes by the cable guides 125. An inner end of each cable guide 125 is supported on an inner surface of the corresponding electrode 111, 112. An annular plate 126 which is supported on the fixing bracket 120 or the movable bracket 321 is provided around an outer portion of each cable guide 125. The cable guides 125 are made of insulation material and function to protect high-voltage cables and prevent generation of an are from the high-voltage cables.
Gaskets 117 are closely interposed between a circumferential inner surface of the casing 100 and circumferential outer surfaces of the respective electrodes 11 and 112 to seal space defined between the casing 100 and the electrodes 111 and 112.
The conventional spark gap switch having the above-mentioned construction can be used as an ultra-wideband electromagnetic wave generation source which is widely used as a high power switching device and conducts functions of storage of electric energy and generation and radiation of ultra-wideband electromagnetic pulses. Furthermore, the electrodes 111 and 112 are configured such that the areas of the surfaces that face each other are comparatively large to increase the capacitance between the electrodes 111 and 112, the distance therebetween is adjusted, and the space therebetween is insulated by high-pressure gas. Therefore, switch storage energy which is an energy source for the generation of electromagnetic waves is comparatively high. Moreover, the shape of each electrode 111, 112 is designed such that it can become an antenna. Thus, mismatching between a switching channel and an antenna is reduced. The electrodes 111 and 112 which form an antenna are enclosed by high-pressure gas with which the spark gap switch is filled. Hence, the electric insulation strength of the electrodes 111 and 112 is enhanced, and the intensity of ultra-wideband electromagnetic waves radiated between the electrodes 111 and 112 is increased.
However, in the conventional spark gap switch for high power ultra-wideband electromagnetic wave radiation, because the surfaces of the electrodes 111 and 112 that face each other are comparatively large and are gently curved to increase the capacitance of the electrodes, although it is ideal that discharge occurs on central portions of the electrodes at which the distance between the electrodes is shortest, there is actually the possibility of discharge occurring at a random position of the surfaces of the two electrodes that face each other.
Furthermore, the conventional spark gap switch is designed such that the maximum diameter of the electrodes is almost the same as the inner diameter of the casing 100. Thus, the spark gap switch is prone to discharge occurring on the inner surface of the casing 100. That is, as shown in FIG. 1, because outer surfaces of rear ends of the electrodes 111 and 112 which face each other make contact with an inner surface of the casing 100, a surface insulation distance d1 formed along the inner surface of the casing 100 may not be sufficiently long.
Therefore, a surface discharge may be caused on the inner surface of the casing 100. As such, if discharge occurs at a position displaced from the central portions of the electrodes 111 and 112, the output power of electromagnetic waves is reduced, and a radiation pattern is deformed, in this case, the spark gap switch cannot serve its intended purpose.